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<div><h2 class="title">
<a name="log"></a>Chapter 1. Boost.Log v2</h2></div>
<div><div class="author"><h3 class="author">
<span class="firstname">Andrey</span> <span class="surname">Semashev</span>
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<div><p class="copyright">Copyright © 2007-2021 Andrey Semashev</p></div>
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<a name="log.legal"></a><p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>).
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<div class="toc">
<p><b>Table of Contents</b></p>
<dl class="toc">
<dt><span class="section"><a href="index.html#log.moti">Motivation</a></span></dt>
<dt><span class="section"><a href="log/how_to_read.html">How to read the documentation</a></span></dt>
<dt><span class="section"><a href="log/installation.html">Installation and compatibility</a></span></dt>
<dd><dl>
<dt><span class="section"><a href="log/installation.html#log.installation.supported_compilers">Supported compilers
      and platforms</a></span></dt>
<dt><span class="section"><a href="log/installation/config.html">Configuring and building the
      library</a></span></dt>
</dl></dd>
<dt><span class="section"><a href="log/defs.html">Definitions</a></span></dt>
<dt><span class="section"><a href="log/design.html">Design overview</a></span></dt>
<dt><span class="section"><a href="log/tutorial.html">Tutorial</a></span></dt>
<dd><dl>
<dt><span class="section"><a href="log/tutorial.html#log.tutorial.trivial">Trivial logging</a></span></dt>
<dt><span class="section"><a href="log/tutorial/trivial_filtering.html">Trivial logging with
      filters</a></span></dt>
<dt><span class="section"><a href="log/tutorial/sinks.html">Setting up sinks</a></span></dt>
<dt><span class="section"><a href="log/tutorial/sources.html">Creating loggers and writing logs</a></span></dt>
<dt><span class="section"><a href="log/tutorial/attributes.html">Adding more information to log:
      Attributes</a></span></dt>
<dt><span class="section"><a href="log/tutorial/formatters.html">Log record formatting</a></span></dt>
<dt><span class="section"><a href="log/tutorial/advanced_filtering.html">Filtering revisited</a></span></dt>
<dt><span class="section"><a href="log/tutorial/wide_char.html">Wide character logging</a></span></dt>
</dl></dd>
<dt><span class="section"><a href="log/detailed.html">Detailed features description</a></span></dt>
<dd><dl>
<dt><span class="section"><a href="log/detailed.html#log.detailed.core">Core facilities</a></span></dt>
<dt><span class="section"><a href="log/detailed/sources.html">Logging sources</a></span></dt>
<dt><span class="section"><a href="log/detailed/sink_frontends.html">Sink frontends</a></span></dt>
<dt><span class="section"><a href="log/detailed/sink_backends.html">Sink backends</a></span></dt>
<dt><span class="section"><a href="log/detailed/expressions.html">Lambda expressions</a></span></dt>
<dt><span class="section"><a href="log/detailed/attributes.html">Attributes</a></span></dt>
<dt><span class="section"><a href="log/detailed/utilities.html">Utilities</a></span></dt>
</dl></dd>
<dt><span class="section"><a href="log/extension.html">Extending the library</a></span></dt>
<dd><dl>
<dt><span class="section"><a href="log/extension.html#log.extension.sinks">Writing your own sinks</a></span></dt>
<dt><span class="section"><a href="log/extension/sources.html">Writing your own sources</a></span></dt>
<dt><span class="section"><a href="log/extension/attributes.html">Writing your own attributes</a></span></dt>
<dt><span class="section"><a href="log/extension/settings.html">Extending library settings support</a></span></dt>
</dl></dd>
<dt><span class="section"><a href="log/rationale.html">Rationale and FAQ</a></span></dt>
<dd><dl>
<dt><span class="section"><a href="log/rationale.html#log.rationale.why_str_lit">Why string literals as scope
      names?</a></span></dt>
<dt><span class="section"><a href="log/rationale/why_weak_scoped_attributes.html">Why scoped
      attributes don't override existing attributes?</a></span></dt>
<dt><span class="section"><a href="log/rationale/why_weak_record_ordering.html">Why log records
      are weakly ordered in a multithreaded application?</a></span></dt>
<dt><span class="section"><a href="log/rationale/why_attribute_manips_dont_affect_filters.html">Why
      attributes set with stream manipulators do not participate in filtering?</a></span></dt>
<dt><span class="section"><a href="log/rationale/why_not_lazy_streaming.html">Why not using lazy
      streaming?</a></span></dt>
<dt><span class="section"><a href="log/rationale/why_not_log4j.html">Why not using hierarchy
      of loggers, like in log4j? Why not Boost.Log4j? Etc.</a></span></dt>
<dt><span class="section"><a href="log/rationale/fork_support.html">Does Boost.Log support process
      forking?</a></span></dt>
<dt><span class="section"><a href="log/rationale/init_term_support.html">Does Boost.Log support
      logging at process initialization and termination?</a></span></dt>
<dt><span class="section"><a href="log/rationale/why_crash_on_term.html">Why my application crashes
      on process termination when file sinks are used?</a></span></dt>
<dt><span class="section"><a href="log/rationale/namespace_mangling.html">Why my application
      fails to link with Boost.Log? What's the fuss about library namespaces?</a></span></dt>
<dt><span class="section"><a href="log/rationale/msvc_link_fails_lnk1123.html">Why MSVC 2010
      fails to link the library with error LNK1123: failure during conversion to
      COFF: file invalid or corrupt?</a></span></dt>
</dl></dd>
<dt><span class="section"><a href="log/reference.html">Reference</a></span></dt>
<dd><dl>
<dt><span class="section"><a href="log/reference.html#top_level_headers">Top level headers</a></span></dt>
<dt><span class="section"><a href="core_components.html">Core components</a></span></dt>
<dt><span class="section"><a href="attributes.html">Attributes</a></span></dt>
<dt><span class="section"><a href="expressions.html">Expressions</a></span></dt>
<dt><span class="section"><a href="logging_sources.html">Logging sources</a></span></dt>
<dt><span class="section"><a href="sinks.html">Sinks</a></span></dt>
<dt><span class="section"><a href="utilities.html">Utilities</a></span></dt>
<dt><span class="section"><a href="other_libraries_support_layer.html">Other libraries support layer</a></span></dt>
</dl></dd>
<dt><span class="section"><a href="log/changelog.html">Changelog</a></span></dt>
<dt><span class="section"><a href="log/todo.html">TODO in future releases</a></span></dt>
<dt><span class="section"><a href="log/acknowledgments.html">Acknowledgments</a></span></dt>
</dl>
</div>
<div class="section">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="log.moti"></a><a class="link" href="index.html#log.moti" title="Motivation">Motivation</a>
</h2></div></div></div>
<p>
      Today applications grow rapidly, becoming complicated and difficult to test
      and debug. Most of the time applications run on a remote site, leaving the
      developer little chance to monitor their execution and figure out the reasons
      for their failure, once it should happen. Moreover, even the local debugging
      may become problematic if the application behavior depends heavily on asynchronous
      side events, such as a device feedback or another process activity.
    </p>
<p>
      This is where logging can help. The application stores all essential information
      about its execution to a log, and when something goes wrong this information
      can be used to analyze the program behavior and make the necessary corrections.
      There are other very useful applications of logging, such as gathering statistical
      information and highlighting events (i.e. indicating that some situation has
      occurred or that the application is experiencing some problems). These tasks
      have proved to be vital for many real-world industrial applications.
    </p>
<p>
      This library aims to make logging significantly easier for the application
      developer. It provides a wide range of out-of-the-box tools along with public
      interfaces for extending the library. The main goals of the library are:
    </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
          Simplicity. A small example code snippet should be enough to get the feel
          of the library and be ready to use its basic features.
        </li>
<li class="listitem">
          Extensibility. A user should be able to extend functionality of the library
          for collecting and storing information into logs.
        </li>
<li class="listitem">
          Performance. The library should have as little performance impact on the
          user's application as possible.
        </li>
</ul></div>
</div>
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